Development of battery terminal seal for sealing electrolyte for periods of three to five years is discussed. Operating conditions of battery are defined. Components of electrolyte seal and method of production are reported. Schematic diagrams of device are included

Medwid, D. W.

Nagle, W. J.

Snider, W. E.

English

NASA Technical Reports Server

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September 1972
	 B72-10581 
NASA TECH BRIEF 
Lewis Research Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Improved Silver-Zinc Battery-Terminal Seals 
One-Piece Battery Terminal
Figure 1. 
The problem: 
To develop a battery terminal seal capable of sealing 
an electrolyte for long time periods (3-5 years) with zero 
leakage. Present terminal seals, such as shown in Figure 
1, develop leaks after a relatively short time (approxi-
mately nine months), thus limiting battery operating 
life.
The battery terminal seal integrity must be main-
tained under the operational voltage, a vacuum, and 
temperature cycling from 21 to 60°C (70 to 1400F). 
S
In present terminal designs, a single-piece unit with 
three "0" rings is potted with an epoxy, assembled in
the battery cover, and further potted at the interior and 
exterior ends. Failure by electrolyte migration has been 
experienced with all such terminals in plastic battery 
cases built to date. 
The solution: 
Eliminate electrolyte migration paths to the outside 
by the use of a two-piece battery terminal having only 
internal threads and no epoxy potting internal to the 
seals.
(continued overleaf) 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19720000580 2020-03-17T03:35:33+00:00Z
Two Piece Terminal 
Ethylene 
Propylene	 Battery Output 
"0" Ring #3 Terminal Halt 
Epoxy Seal #4
-	 - --	
- 1 
Ethylene	
mon 
Propylene	 Ob 
Epoxy Seal #1	
Battery Plate 
Attachment 
Terminal Halt 
Figure 2. 
How it's done: 
The terminal was fabricated in two pieces (Figure 
2). The design provides four separate sealing barriers: 
(1) an interior-end epoxy seal, (2) an elastomeric flat 
washer under compression, (3) an ethylene propylene 
"0" ring also under compression, and (4) an exterior 
epoxy seal. For leakage failure to occur, the ions must 
migrate through three annuli formed by four different 
seals. The seals comprise three different sealing methods. 
Batteries with these redesigned terminal seals have 
been placed in various positions and subjected to thermal 
cycling with no signs of the potassium hydroxide electro-
lyte leaking through the terminals after 21 months of 
testing. Tests are continuing. These terminal seals can 
be used for other types of long-life alkaline batteries, 
and it is planned that these seals will be used in other 
battery systems. 
Notes: 
1. The following documentation may be obtained from: 
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.95)
Reference: NASA TM-X-68067 (N72-24051), 
Nonleaking Battery Terminals 
2. Technical questions may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B72-10581 
Patent status: 
Inquiries concerning rights for the commercial use 
of this invention should be addressed to: 
Patent Counsel 
Mail Stop 500-311 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Source: William E. Snider,
Davis W. Medwid, and

William J. Nagle
Lewis Research Center
(LEW-1 1615) 
B72-10581
	 Category ol,06


Improved silver-zinc battery-terminal seals

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